grade 9 science unit chemistry

Ionic compounds

Compounds formed between metal and non-metal ions.

Negative ions

Atoms that gain electrons and have a negative charge.

Positive ions

Atoms that lose electrons and have a positive charge.

Electrostatic forces

Strong attractive forces between positive and negative ions.

Crystal lattice structure

The organized pattern of ions in ionic compounds.

Melting point of salt

840 degrees Celsius.

Boiling point of salt

1464 degrees Celsius.

Solubility of ionic compounds in water

Ionic compounds are usually soluble in water.

Conductivity of ionic compounds

Ionic compounds conduct electricity when dissolved or melted.

Matter

Anything that takes up space and has mass.

Pure substances

Matter consisting of only one type of particle.

Elements

Pure substances that cannot be broken down further.

Compounds

Substances composed of two or more elements that can be broken down.

Mixtures

Combinations of two or more different particles.

Mechanical mixture

A heterogeneous mixture where different components can be seen.

Solution

A homogeneous mixture that appears uniform throughout.

Filtration

A process to separate particles from a fluid by filtering.

Distillation

A separation method based on differences in boiling points.

Dissolving

A method in which a solute mixes with a solvent.

Particle theory of matter

A theory explaining the behavior of particles in matter.

Kinetic energy

The energy of particles related to their motion.

Solids

States of matter where particles are tightly packed and vibrate.

Liquids

States of matter where particles are spaced apart and slide past one another.

Gases

States of matter where particles are far apart and move quickly.

Qualitative properties

Properties observed without changing the substance.

Quantitative properties

Properties that can be measured and expressed numerically.

Melting point

The temperature at which a substance transitions from solid to liquid.

Boiling point

The temperature at which a substance transitions from liquid to gas.

Density

The mass of a substance per unit volume.

Electrical conductivity

The ability of a substance to conduct electricity.

Molecular (covalent) compounds

Compounds formed when nonmetals share electrons.

Covalent bond

A bond formed when two atoms share a pair of electrons.

Intermolecular forces

Attractions between molecules in molecular compounds.

Solubility of molecular compounds

Some dissolve in water; others do not.

Conductivity of molecular compounds

Molecular compounds never conduct electricity.